Lapidary drill



Feb. 3, 1953 E. L. COX ET AL LAPIDARY DRILL Filed Feb. 16. 1952 Flc.

JNVENTORS /VOMHNHNYE -BER L. COX

BYMMMW HTTCRNEYJ Patented Feb. 3, 1953 LAPIDARY DRILL Eber L. Cox, Akron, and Norman H. Nye, Cuyahoga Falls, Ohio Application February 16, 1952, Serial No.` 271,888

1 Claim. 1

This invention relates to lapidary drills for forming holes or indentations in stones and similar articles, and, more particularly, is concerned with relatively inexpensive apparatus of the indicated type.

Heretofore, drills for forming holes in stones have been provided but so far as we are aware, these drills are relatively heavy, expensive devices which can only be purchased by commercial shops or manufacturers or by wealthy clubs of lapidary enthusiasts. Known equipment cannot ordinarily be purchased by an individual or by small organizations interested in working with stones.

It is the general object of our invention to avoid and overcome the foregoing and other difficulties of and objections to known apparatus by the provision of an improved relatively inexpensive, lightweight lapidary drill having a comparatively high eiciency and an excellent performance.

Another object of our invention is the provision of ay lapidary drill incorporating a relatively simple but highly satisfactory differential mechanism for repeatedly lifting the drill away from the work piece and for dropping the drill back into engagement to break out the small boss or knob of stone present at the bottom of the hole being drilled.

Another object of our invention is to provide apparatus of thecharacter described in which adjustable resilient means are incorporated for controlling the striking power of the drill in its movement back into engagement with the work.

The foregoing objects of our invention, and other objects which will become apparent as the description proceeds, are achieved by the provision of apparatus including a frame, a shaft rotatably journaled in the frame, a chuck on the shaft, a drill in the chuck, a bed adjustably carried by the frame, adjustable pressure resilient means for holding the shaft towards the bed. a pair of differential diameter pulleys on the shaft, the pulley nearest the drill being free on the shaft but being held by an arm of the frame against movement toward the bed, the other pulley being fixed to the shaft, cam means carried between the pulleys and by at least one of the pulleys for moving the pulleys apart against the action of the resilient means as one pulley overtakes the other and for raising the drill out of engagement with a work piece mounted on the bed and for then dropping the drill back into engagement with the work piece, a motor, an idler pulley on the frame, and an endless belt running from the motor around one pulley on the shaft, around idler pulley, around the second pulley on the shaft, and back to the motor.

For a better understanding of the invention, reference should be had to the accompanyin drawing, wherein:

Figure l is a side elevation, partially broken away, of one apparatus embodiment incorpo-v rating the principles of our invention;

Figure 2 is a plan view of the apparatus illustrated in Figure 1;

Figure 3 is a fragmentary view of the differential pulleys incorporated with the apparatus and illustrating the pulleys substantially in the drop-off position;

Figure 4 is a view taken on line IV-IV of Figure 3.

In the drawings, the numeral I0 indicates generally a frame having a base portion I2, for example resting upon a table I4. The frame I8 also includes integral and parallel horizon` tally extending arm portions I6, I8 and 210. The lowermost arm I6 adjustably carries a bed 22, and this can be accomplished by securing a post 24 to the bed, the post being slidably received in a hole in the arm I6 and adjustably secured in place by a screw 26. The bed 22 is, of course, adapted to receive the work piece to be drilled or indented.

Rotatably mounted in the arms I8 and 20 is a shaft 28 which has a chuck 30 secured to its lower end, the chuck removably receiving a drill 32 or other tool. The shaft 28 canbe moved upwardly against the action of a compression spring 34, and the compression of the spring is adjustably controlled by means of a collar 36 fastened to the shaft 28 by a thumb screw 38.

Also mounted on the shaft 28 are a pair of differential pulleys 40 and 42, and by the term differential is meant that the pulleys are of different effective diameter, and in the drawings this difference in diameter has been somewhat exaggerated so as to more strikingly illustrate the structure and operation thereof. The lower pulley 40 rests on a bearing 44 carried by the arm I8 and the pulley 40 is free on the shaft 28. The upper pulley 42 is xed to the shaft 28 as by a pin 46.

Cam means are positioned between the pulleys 40 and 42, being connected to one or both of the pulleys, such means comprising, for example. a wedge-shaped element 48 on pulley 40 and an oppositely inclined wedge-shaped element 50 on pulley 42.

An electric motor or other prime mover 52 is adapted to be mounted on the table It, the motor shaft carrying a pulley 54 on which an endless belt 56 is engaged. One side of the belt 56 runs over a pulley 58 mounted on the frame so that the belt 56 is in alignment with pulley 42, the belt running around this pulley and around an idler pulley 60 mounted at a slightly inclined angle on the frame I0. The incline of the idler pulley 60 is such that the belt 56 extending around the idler pulley is brought into alignment with pulley 40. The belt passing around pulley 40 travels over a pulley 52 likewise mounted on the frame and back to the pulley 54 to complete its endless path.

In the operation of the apparatus as described, a Work piece is secured upon the bed 22 which is adjusted vertically to bring the work piece into engagement with the drill 32 and to somewhat compress spring 34, the entire drill 32, chuck 30 and shaft 23 being raised or pushed upwardly a desiredamount for this purpose. The usual dam of plastic material is built around the work piece area to be drilled and the darn is at least partially,v lled with a solution of abrasive paste. Now the motor 52 is started and belt 55 drives pulleys 40 and 52. The rotation of pulley 42 rotates shaft 28 and drill 32, as will be evident, but, in addition, the slightly smaller pulley diameter of pulley 42 causes it to be driven slightly faster than the slightly larger diameter pulley 40, so that the cam elements 48 and 50 gradually move into engagement and then climb up on each other. As the element 50 begins to climb up upon element i8 the drill 32 is moved out of engagement with the work piece and to the position shown in Figure 3. Further movement of the cam element 50 over the cam element 48 causes the elements to clear each other, whereupon the pulley 42 and shaft 28 is given a sharp downward motion by the energy stored in spring 3d to cause the end of the drill32 to strike or pound against the bottom ofthe hole being drilled. This causes the knob or boss at the center of the hole to fracture with the chips or portions thereof being carried away in the normal drilling operation. It will be understood, of course, that the action of the drill 32 operating through the abrasive solution on the work piece causes the formation of the knob or boss at the center of the hole inasmuchV as the abrasive action is the greatest at the periphery of the drill and is substantially nil at the exact center of the drill. If

a greater striking force is required on the drill the tension of spring 34 can be enhanced by loosening screw 39 and moving the collar 35 upwardly to compress the spring more tightly with the collar 36 being locked in place by again tightening the screw 38.

We have found that the various objects of our invention are achieved by the provision of apparatus of the type described. The apparatus is relatively light and inexpensive, and yet has been found to be highly efficient in operation.

While in accord with patent statutes we have specically illustrated one best known embodiment of the invention, it is to be particularly understood that we are not to be limited thereto or thereby, but that the scope of our invention is defined in the appended claim,

What is claimed is:

A drill for stones and the like including a frame, a shaft rotatably journaled in the frame, a chuck on the shaft, a drill in the chuck, a bed adjustably carried by the frame for movement to or from the drill, adjustable pressure resilient means for holding the shaft towards the bed, a pair of differential diameter pulleys on the shaft, the pulley nearest the drill being free on the shaft but being held by an arm of the frame against movement toward the bed, the other pulley being xed to the shaft, cam means carried between the pulleys and by at least one of the pulleys for moving the pulleys apart against the action of the resilient means as one pulley overtakes the other and for raising the drill out of engagement with a work piece mounted on the bed and for then dropping the drill back into engagement with the work piece, a motor, an idlerpulley on the frame, and an endless belt running from the motor around one pulley on the shaft, around the idler pulley, around the second pulley on the shaft and back to the motor.

EBER L.Y COX. NORMAN H.

REFERENCES CTED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 463,973 Palmer Nov. 24, 1891 1,318,466 Taylor Oct. 14, 1919 2,293,100 Baumg0ld- Aug.'18, 1942 2,372,088 Kaveny Mar. 20, 1945 

